The present invention relates generally to electro-optical systems, and more particularly, to an electro-optical system having a ball turret and an exterior thermal reference source.
Typically, one or more thermal reference source(s) are an integral part of a sensor assembly used in an electro-optical system, such as those manufactured by the assignee of the present invention. Each thermal reference source(s) is placed within the field-of-view of a detector by repositioning a mirror and extending the travel of a scanner. This requires unnecessary modification of various components of the system. It would be desirable to eliminate such additional complications.
Three field of view electro-optical systems typically use reflective optics for all three (wide, medium and narrow) fields of view to ensure that the optical transmission characteristics are substantially equal in all fields of view. Calibrating the detector by viewing a thermal reference source using medium field of view optics is of little use if the transmission characteristics of wide and narrow fields of view optics are substantially different than those of the medium field of view optics. It would be desirable to have a system that improves upon the ability to calibrate the system.
Thermal reference sources are typically used with staring detector arrays, such as those used on INPP and V22 systems, for example, developed by the assignee of the present invention. However, moving mirrors have not been used to place those thermal reference sources within the field of view of the detector.
Other electro-optical systems use a shutter as a uniform temperature thermal reference source. The temperature of the shutter is typically not controlled and is not preferred for use in advanced electro-optical systems.
Accordingly, it is an objective of the present invention to provide for an improved multiple field of view electro-optical system employing a ball turret and an exterior thermal reference source.